ASTROPHYSICS: From Black Holesto the First Stars

(Lecture 1: Introduction)

Instructor: Volker BrommTA: Jarrett Johnson

The University of Texas at Austin

Astronomy 353

(Spring 2007)

Physics of Stellar Remnants

White DwarfsNeutron Stars

Black Holes

~ 10,000 km(àààà Earth)

~ 10 km~ 3 km

Quantum Pressure in Stellar Remnants

• often called: ``degeneracy pressure’’

How are Compact Objects born?

àààà Brief Overview of Stellar Evolution

Supernova (SN) Explosions

• extremely energetic and violent events

SN Remnants (e.g., Crab Nebula)

Albert Einstein: Revolutionary of Physics

• 1879 (Ulm) – 1955 (Princeton)

• revolutionized concepts ofspace, time, and gravity- Special Relativity (1905):

à E=mc2

- General Relativity (1915):à new theory of gravity

• co-founder of quantum theoryà photons

General Theory of Relativity (1915-16)

• Principle 1: “Matter tells space how to curve”

• matter creates `dimples’ in otherwise flat spacetime!

General Theory of Relativity (1915-16)

• Principle 2: “Curved space tells matter how to move”

• particles move through spacetime along paths ofleast resistance (technically: `geodesics’)!

General Theory of Relativity (1915-16)

• Einstein’s Field equations:

• a `tensor equation’ à quite complicated(10 coupled non-linear differential equations)

(curvature of space) (matter content)

Solving Einstein’s Equations of GR

• 1916: Karl Schwarzschild predicts black holes

Karl Schwarzschild (1873-1916)

`Schwarzschild radius’

Gravitational Collapse of Massive Star

• surprising result:for far-away observer,star’s surface `freezes’at event horizon

(i.e., never crosses over)

• however: for observerriding on top of collapsing surface, thisonly takes a finite time!

• Q: How can both perspectives be right?

Quantum Mechanics of Black Holes

• Hawking radiation

à Black Holes slowly evaporate!

The First Stars

• formed at the end of the `Cosmic Dark Ages’

àààà First stars are predicted to be much more massive thanstars today!

The First Supernova-ExplosionGas density

~ 1 kpc

• ESN~1053ergs

• Complete Disruption(PISN)

The First Stars• forging the first heavy elements (beyond helium)

à Possibly unique kind of supernova: Pair-instability Supernova

COURSE WEBSITE:

www.as.utexas.edu/astronomy/education/spring07/bromm/353.php

• announcments/updates

• lecture notes

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